Flow-through Fluorescence-based Optosensor for the Screening of Zinc in Drinking Water

Abstract

A single and rapid solid surface fluorescence-based flow-through optosensor has been developed for the screening of trace amounts of Zn(II) in drinking water samples. The proposed method is based on the transient immobilization of the target species: the complex formed between Zn(II) and the fluorogenic reagent p-(tosylamino)quinoline (p-TAQ) on an appropriate solid support (C₁₈ silica gel). The fluorescence of the complex was continuously monitored at an emission wavelength of 495 nm upon excitation at 377 nm. The instrumental, chemical and flow-injection variables were carefully investigated and optimized. The sensor was calibrated over the range of 5 - 125 ng mL^-1, obtaining a limit of detection of 0.9 ng mL^-1, a RSD of 1.8%, with a sampling frequency of 20 h^-1. The proposed method was successfully applied to different drinking water samples with recoveries between 98 and 104%.